Support for asynchronous non-blocking calls available in the sandbox

[Jean-Sebastien Delfino]

I checked a first implementation of support for async non-blocking calls 
in the sandbox. Directory sandbox/sebastien/java/sca/async contains the 
runtime code, sandbox/sebastien/java/samples/helloworldasync contains an 
asynchronous variation of the helloworld sample. More details about how 
this code works are in http://issues.apache.org/jira/browse/TUSCANY-223.

Could people in the group please take a look and see if you're 
(reasonably) happy with this initial implementation? If there's no 
objection I'd like to move this to the sca/core project in the next 
couple of days.

There are still some limitations and temporary workarounds in this code, 
I'm probably going to need help to go from there and improve this 
initial implementation. I'm also looking for a better sample than 
helloworld to demonstrate the async capability... Anybody interested in 
helping with this?

--
Jean-Sebastien